The Kurds have had long-standing ambitions to secede from Iraq, and officials have talked up the idea of withdrawing from Iraq as soon as the war with ISIS is over. The US has opposed this, saying they want a “unified” Iraq.

The biggest question arising from a possible secession of the KRG is what territory they’ll take with them, as early in the ISIS war they seized key oil-producing regions, including Kirkuk, and more recently have been expelling Arabs from the Sinjar area to try to make it a Kurdish-Yazidi dominated region too.

Iraqi PM Hayder Abadi’s office offered a warning against any unilateral votes by the KRG, saying they would be “against the constitution and illegal.” The central government has seen the risk of secession coming for awhile, and has pushed against arming the Kurds to fight ISIS on the fear that the heavily armed Kurdish Peshmerga would be able to fight a war of secession.

The legal question may matter less and less as time goes on, however, as the Peshmerga has gotten a lot of weaponry, and Iraq’s military is scarcely in a position to contest a secession by anyone with so much of the country already under ISIS control.

Iraqi Kurdish secession could also fuel a regional split, with the Kurdish YPG in northeastern Syria and growing Kurdish unrest in southeastern Turkey, both of those countries could find themselves looking to join a unified Kurdistan.